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Heat Staking

Heat Setting


Shrink Fitting

Susceptor Heating

Pre-Heating for Welding

Annealing Incoloy Tubing

annealing in a controlled atmosphere

Research Objective

To anneal a continuous feed of incoloy stainless steel tubing at 2000°F in a protective atmosphere with a quick cool-down, and to eliminate need for additional sandblasting operation.

Parts & Materials Description

Incoloy 840 stainless steel tubing, .310” diameter

Temperature Required


Induction Heating Equipment

20 kW RF power supply, 11-turn helical inductor (coil) with .8” O.D.

Operating Frequency

253 kHz

Heating Procedure

A specially-designed 11-turn helical inductor was utilized to provide even heat to the stainless steel tubing. After initial tests were conducted to establish time-to-temperature and heating profiles, a length of tubing was placed on a PacSci carriage in a protective atmosphere of nitrogen. The carriage conveyed the tubing through the inductor at a rate of 1.4 inches per second. The 20kW power supply and carriage were activated simultaneously. Optical sensors monitored the temperature of the steel tubing as it passed through the inductor, and at 100 inches away from the inductor. The power supply was turned off as the trailing end of the tube entered the inductor.


Consistent, repeatable results were achieved with the 20kW power supply and a feed rate of 1.4 inches per second. The temperature of the steel tube reached 2000°F as it left the inductor and cooled to 950° at a distance of 100 inches from the inductor. Two or three water-cooled rollers could be utilized to reduce the cooling time as needed.

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